Multilayered cap barrier in microelectronic interconnect structures

ABSTRACT

Structures having low-k multilayered dielectric diffusion barrier layer having at least one low-k sublayer and at least one air barrier sublayer are described herein. The multilayered dielectric diffusion barrier layer are diffusion barriers to metal and barriers to air permeation. Methods and compositions relating to the generation of the structures are also described. The advantages of utilizing these low-k multilayered dielectric diffusion barrier layer is a gain in chip performance through a reduction in capacitance between conducting metal features and an increase in reliability as the multilayered dielectric diffusion barrier layer are impermeable to air and prevent metal diffusion.

RELATED APPLICATIONS

This application is a divisional of U.S. application Serial No.10/648,884, filed Aug. 27, 2003, which claims benefit of U.S.Provisional application Serial No. 60/463,758, filed Apr. 17, 2003.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the utilization of a multilayered capbarrier layer that has a low composite dielectric constant (k<4.0) andhas barrier properties to metal diffusion and air permeation. Moreparticularly, the present invention relates to the use of themultilayered cap barrier layer in metal interconnect structures that arepart of integrated circuits and microelectronic devices. The primaryadvantage that is provided by the present invention is the reduction inthe capacitance between conducting metal features, e.g., copper lines,that results in an enhancement in overall chip performance. Methods forthe utilization, compositions of matter, and structures that implementthe barrier films are also described.

2. Background Art

The utilization of materials that serve as diffusion barriers to metalin metal interconnect structures, that are part of integrated circuitsand microelectronic devices, is typically required to generate reliabledevices as low-k interlayer dielectrics do not prohibit metal diffusion.The placement of these materials in the interconnect structure candiffer and will be dependent upon their qualities and the means in whichthey are deposited and processed. Both barrier layers comprised of metaland dielectrics are commonly utilized in interconnect structures.

Diffusion barrier layers, comprised of metal and metal containingmaterials including, for example, tantalum, tungsten, ruthenium,tantalum nitride, titanium nitride, TiSiN, etc., often serve as linerswhereby they form a conformal interface with metal conductingstructures. Normally, these materials are deposited by chemical vapordeposition (CVD), plasma-enhanced chemical vapor deposition (PECVD),atomic layer deposition, (ALD), sputtering, thermal evaporation, andother related approaches. To utilize these materials as barrier layers,the metal barrier layers must be conformal to conducting metal lines andcannot be placed as blanket layers that would serve as conductingpathways between metal lines. One limiting criteria for these barrierlayers is that their contribution to the resistivity of conducting metallines must not be excessively high; otherwise, the increase in the totalresistance of the metal conducting structures would result in reducedperformance.

Diffusion barrier layers comprised of dielectrics including, forexample, silicon nitrides, silicon carbides, and silicon carbonitrides,are also utilized in microelectronic devices. These materials arenormally deposited by chemical vapor deposition (CVD) andplasma-enhanced chemical vapor deposition (PECVD) approaches and can bedeposited as continuous films, e.g., as cap barrier layers. Unlikediffusion barrier layers comprised of metal, the dielectric layers canbe deposited as blanket films and can be placed between conducting metallines. In doing so, these dielectric layers contribute to thecapacitance between metal lines. A limiting constraint of these systemsis their relatively high dielectric constants (k=4.5-7) that result in asubstantial increase in the effective dielectric constant between metallines and leads to reduced device performance. Decreasing the filmthickness of these barrier layers can lead to reductions in theeffective dielectric constant; however, insufficiently thick layers maynot be reliable and nevertheless may have significant contributions tothe effective dielectric constant.

Barrier layer films that are generated by spin-coating, or other solventbased approaches, that prohibit copper diffusion have also beenproposed. These systems can be polymers that may be cured at elevatedtemperatures to produce rigid, crosslinked systems that are thermallystable to temperatures in excess of 400° C. A primary advantage of manyof these systems is the low dielectric constant that these materialsexhibit; dielectric constants of 2.6 have been measured. Examples ofsuch systems include: polysilazanes, polycarbosilanes,polysilsesquiazanes, polycarbosilazanes, etc.

In addition to copper diffusion barrier properties, barrier propertiesto air permeation is highly desirable for barrier layer films. Airpermeation through barrier layer films can adversely lead to oxidationof conducting metal features and result in reduced reliability and/orperformance. Some dielectric copper diffusion barriers deposited by CVDand related approaches have been observed to display air barrierproperties due to their high density. However, many of the low-k copperdiffusion barriers applied by solvent based approaches do not serve as abarrier to air permeation due to their relatively open structure whichmay contain a significant portion of voids or free volume.

SUMMARY OF THE INVENTION

The present invention relates to interconnect structures including amultilayered dielectric diffusion barrier layer having a low dielectricconstant (k<4.0) and which serves as a barrier to metal diffusion andair permeation. The multilayered dielectric diffusion barrier layer ofthe present invention is comprised of sublayers where at least one airbarrier sublayer is a dielectric deposited by CVD or a related processand at least one low-k sublayer is a barrier dielectric deposited by asolvent based approach. The advantage of utilizing both types ofdielectrics is that the multilayered dielectric diffusion barrier layerwill exhibit a composite dielectric constant that is significantly lowerthan CVD deposited barrier dielectrics while maintaining barrierproperties to air permeation which may not be afforded by low-k solventdeposited barrier dielectrics alone.

The present invention can be employed in any microelectronic device thatutilizes metal interconnect structures including, for example, highspeed microprocessors, application specific integrated circuits (ASICs),and memory storage. The utilization of the multilayered dielectricdiffusion barrier layer of the present invention is extremelyadvantageous in comparison to prior art approaches, as it results inmicroelectronic devices with increased performance through a reductionin the capacitance between conducting metal lines while maintainingproperties conducive to generating reliable structures.

The inventive structure may be comprised of at least one conductingmetal feature, formed on a substrate, with the substrate furthercomprising at least one insulating layer surrounding the conductingmetal feature. The insulating layer may surround the at least oneconducting metal feature at its bottom, top, and lateral surfaces. Theinventive structure may further comprise at least one conductive barrierlayer disposed at least at one interface between the insulating layerand the at least one conducting metal feature. The combination of the atleast one conducting metal feature and the insulating layers, may berepeated to form a multilevel interconnect stack.

The structure may be one of a silicon wafer containing microelectronicdevices, a ceramic chip carrier, an organic chip carrier, a glasssubstrate, a gallium arsenide wafer, a silicon carbide wafer, a galliumwafer, or other semiconductor wafer.

The substrate may be a silicon wafer containing electronic devices. Thesubstrate consists in part, or in entirety, of Si, SiO₂, SiGe, Ge, Ga,GaAs, Hg, HgTd, InP, In, Al, or any other semiconducting material thatis inorganic or organic in nature.

In a first embodiment of the present invention, an interconnectstructure including the multilayered dielectric diffusion barrier layercomprised of two or more dielectric sublayers that exhibit metaldiffusion barrier properties is described. At least one of thesesublayers is an air barrier sublayer that may be a CVD depositeddielectric that is impermeable to air diffusion. At least another ofthese sublayers is a low-k sublayer that is applied by any solvent basedapproach (e.g., spin-coating) and has a dielectric constant less than3.0. The low-k sublayer may be placed atop and/or below the air barriersublayer. Optionally, adhesion promoters may be applied at any of theinterfaces in the multilayered dielectric diffusion barrier layer or atinterfaces between the sublayers.

In a first example of the first embodiment, the multilayered dielectricdiffusion barrier layer is utilized as a cap barrier layer. Theremaining dielectrics in the interconnect structure may be comprised ofa via level dielectric, a line level dielectric (which may be identicalin composition to the via level dielectric), optional hardmask layers,and optional buried etch stop layers.

In a second example of the first embodiment, a multilayered dielectricdiffusion barrier layer is utilized simultaneously as a cap barrierlayer and a via level dielectric. The remaining dielectrics in theinterconnect structure may be comprised of a line level dielectric,optional hardmask layers, and optional buried etch stop layers.

In a third example of the first embodiment, a multilayered dielectricdiffusion barrier layer is utilized as a cap barrier layer and is atopan interconnect structure having an interlayer dielectric comprised ofat least two dielectrics where the via level dielectric, which isunderneath metal lines, chemically differs from the dielectrics in otherregions.

The multilayered dielectric diffusion barrier layer of the presentinvention has a composite dielectric constant of less than 4.0,prohibits metal diffusion, serves as a barrier to air permeation, and isthermally stable to temperatures greater than 400° C. The multilayereddielectric diffusion barrier layer of the present invention may alsocontain porosity that further reduces the dielectric constant. The poresmay be generated by a removal of a sacrificial moiety that may bepolymeric. The pores may also be generated by a process that involves anelimination of a high boiling point solvent. The pores may have a sizescale of 0.5-20 nanometers and may have a closed cell morphology.

In a second embodiment of the present invention, a method to produce themultilayered dielectric diffusion barrier layer is described. Themultilayered dielectric diffusion barrier layer of the present inventionis generated atop an interconnect structure having exposed metal anddielectric features. Each sublayer is then deposited by either chemicalvapor deposition (or related approaches) or by solvent based processes(e.g., spin coating). After each deposition step, the films may beannealed at elevated temperatures (100°-500° C.), exposed to electronbeams, and/or irradiated with ultraviolet light, prior to the depositionof the subsequent sublayer. Optionally, adhesion promoters may beapplied at any interface of the multilayered dielectric diffusionbarrier layer or at interfaces between the sublayers.

In a third embodiment of the present invention, compositions of themultilayered dielectric diffusion barrier layer, its sublayers, andprecursors used to generate these layers are described. At least one airbarrier sublayer is produced by a chemical vapor deposition basedprocess whereby the air barrier sublayer is comprised of siliconnitride, silicon carbonitride, or a dielectric having the generalcomposition of Si_(v)N_(w)C_(x)O_(y)H_(z)where 0.1≦v≦0.8, 0≦w≦0.8,0.05≦≦0.8, 0≦y≦0.3, 0.05≦z≦0.8 for v+w+x+y+z=1. At least one othersublayer is deposited by a solvent based approach that utilizes apolymeric preceramic precursor dissolved in solution. Upon filmformation, the polymeric preceramic precursor is converted to aninsoluble low-k sublayer having the general composition of Si_(l N)_(w)C_(x)O_(y)H _(z where) 0.1≦v≦0.8, 0≦w≦0.8, 0.05≦x≦0.8, 0≦y≦0.3,0.05≦z≦0.8 for v+w+x+y+z=1.

Other and further objects, advantages and features of the presentinvention will be understood by reference to the following specificationin conjunction with the annexed drawings, wherein like parts have beengiven like numbers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of a semiconductor device in accordancewith the present invention.

FIG. 2 is a cross sectional view of another semiconductor device inaccordance with the present invention.

FIG. 3 is a cross sectional view of yet another semiconductor device inaccordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In accordance with the first embodiment of the present invention, aninterconnect structure comprising at least one conductive metal feature,with the structure further comprising an interlayer dielectric layercomprised of a line level dielectric and a via level dielectric,surrounding conducting metal features whereby a multilayered dielectricdiffusion barrier layer that is a barrier to metal diffusion and airpermeation is described.

The inventive multilayered dielectric diffusion barrier layer has acomposite dielectric constant less than 4.0, is thermally stable abovetemperatures of 300° C., has a thickness between 10 and 500 nm, and iscomprised of at least two sublayers where at least one sublayer is anair barrier sublayer and at least another sublayer is a low-k sublayer.The multilayered dielectric diffusion barrier layer of the presentinvention may have a variety of configurations including, for example, abilayer with the low-k sublayer atop the air barrier sublayer, a bilayerwith the air barrier sublayer atop the low-k sublayer, or a trilayerwith the air barrier sublayer placed between two low-k sublayers.

The air barrier sublayer is a dielectric that is impermeable to air, hasa dielectric constant that is between 3.4-7.2, has a thickness between 5and 100 nm, may be a barrier to metal diffusion, and is deposited by avapor deposition based process including, for example, chemical vapordeposition, plasma enhanced chemical vapor deposition, physical vapordeposition, or any related process. It may be a dielectric that has acomposition of Si_(v)N_(w)C_(x)O_(y)H_(z) where 0.1≦v≦0.8, 0≦w≦0.8,0.05≦x≦0.8, 0≦y≦0.3, 0.05≦z≦0.8, and v+w+x+y+z=1. Examples of the airbarrier sublayer including, for example, silicon nitride, siliconcarbonitride, silicon oxynitride, silicon dioxide, silicon carbide, andfluorinated glass.

The low-k sublayer is a dielectric that has a dielectric constant lessthan 3.3, is a barrier to metal diffusion, has a thickness between 5 and500 nm, and is generated by a solvent based approach including, but notlimited to: spin coating, spray coating, scan coating, and dip coating.The low-k sublayer may be a dielectric comprised ofSi_(v)N_(w)C_(x)O_(y)H_(z) where 0.1≦v≦0.8, 0≦w≦0.8, 0.05≦x≦0.8,0≦y≦0.3, 0.05≦z≦0.8, and v+w+x+y+z=1. The low-k sublayer may containporosity where the porosity may have a size scale of 0.5-20 nm and mayhave closed cell morphology.

The interconnect structure of the present invention is further comprisedof at least one low dielectric constant material. The low dielectricconstant material may be any dielectric known in the art including, forexample, spin-on systems such as: polysiloxanes, polysilsesquioxanes,polyarylenes, poly(arylene ethers), or dielectric films that aregenerated by vapor deposition approaches which may have a compositionSi_(v)N_(w)C_(x)O_(y)H_(z) where 0.05≦v≦0.8, 0≦w≦0.9, 0.05≦x≦0.8,0≦y≦0.8, 0.05≦z≦0.8 for v+w+x+y+z=1. Furthermore, the inventive lowdielectric constant material may be porous. Finally, the low dielectricconstant material may be air or an inert gas.

In addition, the interconnect structure of the present invention isfurther comprised of conducting metal features which may be comprised ofcopper, silver, gold, aluminum and alloys thereof. The conducting metallines may have a metal at the top surface that reduces theelectromigration characteristics of the interconnect structure that maybe comprised of a composition including: cobalt, tungsten, phosphorous,and combinations thereof. The conducting metal lines may have a moietyat the top surface that reduces the propensity of the metal lines tooxidize. Examples of such moieties include: benzotriazoles, amines,amides, imides, thioesters, thioethers, ureas, urethanes, nitriles,isocyanates, thiols, sulfones, phosphines, phosphine oxides,phosphonimides, pyridines, imidazoles, imides, oxazoles, benzoxazoles,thiazoles, pyrazoles, triazoles, thiophenes, oxadiazoles, thiazines,thiazoles, quionoxalines, benzimidazoles, oxindoles, and indolines.

Furthermore, the inventive interconnect structure is further comprisedof a lining metal containing barrier layers that are used to preventmetal diffusion. The lining metal containing barrier layers may becomprised of: tantalum, tantalum nitride, tungsten, titanium, titaniumnitride, ruthenium, TiSiN, and combinations thereof.

Finally, optional hardmask dielectric and dielectric etch stop layersmay be present in the inventive structure. Illustrative examples as suchdielectric materials include polysiloxanes, polysilsesquioxanes, or anyCVD deposited dielectric having the compositionSi_(v)N_(w)C_(x)O_(y)H_(z) where 0.05≦v≦0.8, 0≦w≦0.9, 0.05≦x≦0.8,0≦y≦0.8, 0.05≦z≦0.8 for v+w+x+y+z=1.

Referring to FIG. 1, in the first embodiment, an example of aninterconnect structure 40, comprised of multiple levels 1000 where eachlevel may consist of a via level 1100 and line level 1200, is shown. Theinterconnect structure contains conducting metal features 33 thattraverse through the structure and may have interfaces with a liningmetal containing barrier 34. The conducting metal features and liningmetal containing barrier are surrounded by dielectrics. The dielectricsin the via level include a low dielectric constant material 32 and theinventive multilayered dielectric diffusion barrier layer 39 that iscomprised of at least two sublayers—the air barrier sublayer 36 and thelow-k sublayer 38. The dielectrics in the line level 1200 include a lowdielectric constant material 31 and an optional hardmask dielectric 41.Optionally, a dielectric etch stop layer 37 may be placed between thelow dielectric constant materials in the via level and line level (32 &31). The low dielectric constant material in the via level and linelevel (32 & 31, respectively) may be identical in composition or maychemically differ.

Referring to FIG. 2, in the first embodiment, an example of anotherinterconnect structure 40, comprised of multiple levels 1000 where eachlevel may consist of a via level 1100 and line level 1200, is shown. Theinterconnect structure contains conducting metal features 33 thattraverse through the structure and may have interfaces with a liningmetal containing barrier 34. The conducting metal features and liningmetal containing barrier are surrounded by dielectrics. The dielectricsin the via level include the inventive multilayered dielectric diffusionbarrier layer 39 that is comprised of at least two sublayers—the airbarrier sublayer 36 and the low-k sublayer 38. The dielectrics in theline level include a low dielectric constant material 31 and an optionalhardmask dielectric 41. Optionally, a dielectric etch stop layer 37 maybe placed between the low dielectric constant materials in the linelevel 31 and the multilayered dielectric diffusion barrier layer 39.

Referring to FIG. 3, in the first embodiment, another example of aninterconnect structure 40, comprised of multiple levels 1000 where eachlevel may consist of a via level 1100 and line level 1200, is shown. Theinterconnect structure contains conducting metal features 33 thattraverse through the structure and may have interfaces with a liningmetal containing barrier 34. The conducting metal features and liningmetal containing barrier are surrounded by dielectrics. The dielectricsin the line level include a low dielectric constant material 43. Thedielectrics in the via level include the identical low dielectricconstant material 43 in regions not directly underlying conducting metallines, a chemically different low dielectric constant material 42 whichis present under conducting metal lines, and the inventive multilayereddielectric diffusion barrier layer. Optionally, a dielectric etch stoplayer 37 may be placed between the low dielectric constant material 42and the lining metal containing barrier 34 that is above it.

An adhesion promoter may be present between the multilayered dielectricdiffusion barrier layer and dielectric layers above and/or below themultilayered dielectric diffusion barrier layer. Also, an adhesionpromoter may be present between the sublayers of the multilayereddielectric diffusion barrier layer. The adhesion promoters may beselected from the group consisting of Si_(a)L_(b)R_(c), wherein L isselected from the group consisting of hydroxy, methoxy, ethoxy, acetoxy,alkoxy, carboxy, amines, halogens, R is selected from the groupconsisting of hydride, methyl, ethyl, vinyl, and phenyl (any alkyl oraryl), a is from 0.25 to 0.5, b is from 0.1 to 0.8, c is from 0 to 0.7,and the sum of a+b+c is 1. Examples of adhesion promoters that may beused in the present invention include: hexamethyldisilazane,vinyltriacetoxysilane, aminopropyltrimethoxysilane, and vinyltrimethoxysilane.

In accordance with the second embodiment of the present invention, amethod of generating a multilayered dielectric diffusion barrier layercomprising: applying a coating of a polymeric preceramic precursor by asolvent based approach, converting the polymeric preceramic precursorinto the low-k sublayer, and applying a coating of an air barriersublayer is described.

The solvent based approach is used to deposit the polymeric preceramicprecursor from solution to produce a film and can be performed by anyprocess known in the art and may be one of: spin coating, spray coating,scan coating, or dip coating. The conversion of the polymeric preceramicprecursor film into the low-k sublayer is through the use of one or acombination of any suitable processes including, for example, thermalcuring, electron irradiation, ion irradiation, irradiation withultraviolet and/or visible light. The thermal curing can be performedunder inert atmospheres and/or at temperatures in excess of 400° C.Crosslinking mechanisms may occur during the conversion of the polymericpreceramic precursor into the low-k sublayer.

Methods used to generate porosity in the low-k sublayer may be utilized.Porosity may be formed by codissolving a sacrificial moiety in thesolution containing the polymeric preceramic precursor. Upon conversionof the polymeric preceramic precursor into the low-k sublayer, thesacrificial moiety may be a polymeric material that degrades into lowmolecular weight byproducts and are expelled from the film.Alternatively, the porosity may be generated from an approach thatutilizes a high boiling point solvent that is expelled from the filmduring the conversion of the polymeric preceramic precursor into thelow-k sublayer.

The air barrier sublayer is applied by any vapor based depositionprocess known in the art including, for example, chemical vapordeposition, plasma enhanced chemical vapor deposition, and physicalvapor deposition. The air barrier sublayer may be annealed through theuse of one or a combination of any suitable processes including, forexample, thermal curing, electron irradiation, ion irradiation,irradiation with ultraviolet and/or visible light. The thermal curingcan be performed under inert atmospheres and/or at temperatures inexcess of 400° C. Further densification of the air barrier sublayer mayoccur during the annealing process.

The annealing of the air barrier sublayer and the polymeric preceramicprecursor into the low-k sublayer can be performed simultaneously.Furthermore, these annealing steps may coincide with the annealingprocess of other layers including the low dielectric constant material,hardmasks, and/or buried etch stops.

Numerous steps can be applied to enhance adhesion of the sublayers tothe other sublayers and also to adjacent layers. One example is theaforementioned use of adhesion promoters. The adhesion promoter may beapplied onto the substrate prior to or after the deposition of anysublayer. For the low-k sublayer, the adhesion promoter may becodissolved in the solution containing the polymeric preceramicprecursor and may segregate to film interfaces either during applicationor during the conversion of the polymeric preceramic precursor into thelow-k sublayer. Alternatively, the adhesion promoter may be applied tothe film comprised of the polymeric preceramic precursor prior to theconversion of the polymeric preceramic precursor into the low-ksublayer. Finally, dry etch processes employing a reactive plasma may beapplied to any of the sublayers, layers underlying any sublayers, andthe film comprised of the polymeric preceramic precursor in order tomodify the surface of the exposed film and enhance adhesion.

Methods used to clean or eliminate any chemicals remaining from otherprocesses may also be applied to the substrate prior to the depositionof the multilayered dielectric diffusion barrier layer. This cleaningmay involve exposing the substrate to acids, bases, and/or organicsolvents. This cleaning may also involve dry etch processes.

In accordance with the third embodiment of the present invention,compositions for the generation of a multilayered dielectric diffusionbarrier layer having a solvent for application of the low-k sublayer bythe solvent based approach, a polymeric preceramic precursor that isconverted to a low-k sublayer, and an air barrier sublayer is described.

The polymeric preceramic precursor may be a silicon containing systemand may be comprised of the following: polysilazanes, polycarbosilanes,polysilasilazanes, polysilanes, polysilacarbosilanes, polysiloxazanes,polycarbosilazanes, polysilylcarbodiimides, polysilsesquiazanes,polysilsesquiazanes, and polysilacarbosilazanes. A highly preferredpolymeric precursor is polyureamethyvinylsilazane (KiON). The polymericpreceramic precursor may contain some component of polysiloxanes orpolysilsesquioxanes. The polymeric preceramic precursor may have pendantfinctional groups bonded to the chain backbone including, hydrido,vinyl, allyl, alkoxy, silyl, and alkyl groups. The polymeric preceramicprecursor may have pendant fuictional groups bonded to the chainbackbone that may have metal binding properties including: amines,amides, imides, thioesters, thioethers, ureas, urethanes, nitrides,isocyanates, thiols, sulfones, phosphines, phosphine oxides,phosphonimides, benzotriazoles, pyridines, imidazoles, imides, oxazoles,benzoxazoles, thiazoles, pyrazoles, triazoles, thiophenes, oxadiazoles,thiazines, thiazoles, quionoxalines, benzimidazoles, oxindoles, andindolines. The molecular weight of the polymeric preceramic precursormay be between 500 and 1,000,000 daltons. The polymeric preceramicprecursor may be a homopolymer, random copolymer, block copolymer, or apolymer blend and can have any chain architecture including linear,networked, branched, and dendrimeric. The polymeric preceramic precursormay have a composition of Si_(v)N_(w)C_(x)O_(y)H_(z) where 0.1≦v≦0.8,0≦w≦0.8, 0.05≦x≦0.8, 0≦y≦0.3, 0.05≦z≦0.8, and v+w+x+y+z=1.

The solvent based approach involves a solution of the polymericpreceramic precursor dissolved in an organic solvent. The organicsolvent may be one or a combination of the following solvents: propyleneglycol methyl ether acetate (PGMEA), propylene glycol methyl ether(PGME), toluene, xylene, anisole, mesitylene, butyrolactone,cyclohexanone, hexanone, ethyl lactate, and heptanone. The solution maycontain an antistriation agent that is codissolved with the polymericpreceramic precursor to produce films of high uniformity. The amount ofantistriation agent may be less than 1% of the solution containing thepolymeric preceramic precursor. An adhesion promoter may also beco-dissolved in the solution containing the polymeric preceramicprecursor. The adhesion promoter may be selected from the groupconsisting of Si_(a)L_(b)R_(c,) wherein L is selected from the groupconsisting of hydroxy, methoxy, ethoxy, acetoxy, alkoxy, carboxy,amines, halogens, R is selected from the group consisting of hydrido,methyl, ethyl, vinyl, and phenyl (any alkyl or aryl), a is from 0.25 to0.5, b is from 0.1 to 0.8, c is from 0 to 0.7, and the sum of a+b+cis 1. The adhesion promoter may be: hexamethyldisilazane,vinyltriacetoxysilane, aminopropyltrimethoxysilane, vinyltrimethoxysilane, and combinations thereof. The adhesion promoter may beless than 2% of the solution containing the polymeric preceramicprecursor.

A sacrificial moiety to produce porosity may be codissolved in thesolution containing the polymeric preceramic precursor. The sacrificialmoiety may be a sacrificial polymeric material that degrades into lowmolecular weight byproducts that are expelled from the film during theconversion of the polymeric preceramic precursor into the low-ksublayer. The sacrificial polymeric material may be one of, acombination of, or a copolymer of: poly(stryenes), poly(esters),poly(methacrylates), poly(acrylates) and poly(glycols), poly(amides),and poly(norbornenes). The sacrificial moiety may be a high boilingpoint solvent.

Upon conversion of the polymeric preceramic precursor into the low-ksublayer, the low-k sublayer may have a composition ofSi_(v)N_(w)C_(x)O_(y)H_(z) where 0.1≦v≦0.8, 0≦w≦0.8, 0.05≦x≦0.8,0≦y≦0.3, 0.05≦z≦0.8 for v+w+x+y+z=1. A more preferred composition forthe low-k sublayer is Si_(v)N_(w)C_(x)O_(y)H_(z) where v=0.16±0.05,w=0.17±0.05, x=0.17±0.05, y=0, z=0.5±0.1 for v+w+x+y+z=1.

The air barrier sublayer may have a composition ofSi_(v)N_(w)C_(x)O_(y)H_(z) where 0.1≦v≦0.8, 0≦w≦0.8, 0.05≦x≦0.8,0≦y≦0.3, 0.05<z≦0.8 for v+w+x+y+z=1. A preferred composition for the airbarrier sublayer is Si_(v)N_(w)C_(x)O_(y)H_(z) where v=0.28±0.05,w=0.12+0.05, x=0.28±0.05, y=0, z=0.32±0.05 for v+w+x+y+z=1. Anopreferred composition for the air barrier sublayer isSi_(v)N_(w)C_(x)O_(y)H_(z) where v=0.28±0.05, w=0, x=0.32±0.05, y=0,z=0.4±0.10 for v+w+x+y+z=1.

While the present invention has been particularly shown and describedwith respect to preferred embodiments thereof, it will be understood bythose skilled in the art that the foregoing and other changes in formsand details may be made without departing from the spirit and scope ofthe invention. It is therefore intended that the present invention notbe limited to the exact forms and details described and illustrated, butfall within the scope of the appended claims.

1. A method of generating a multilayered dielectric diffusion barrierlayer comprising: applying a coating of a polymeric preceramic precursorby a solvent based approach; converting the polymeric preceramicprecursor into the low-k sublayer; and applying a coating of an airbarrier sublayer.
 2. The method of claim 1, wherein the converting ofthe polymeric preceramic precursor into the low-k sublayer comprisesthermal curing, electron irradiation, ion irradiation, irradiation withultraviolet and/or visible light, or any combination thereof.
 3. Themethod of claim 1, wherein an adhesion promoter is applied prior to theapplication of the polymeric preceramic precursor.
 4. The method ofclaim 3, wherein the adhesion promoter is codissolved in a solutioncontaining the polymeric preceramic precursor and segregates to filminterfaces either during application or during said conversion of thepolymeric preceramic precursor into the low-k sublayer.
 5. The method ofclaim 1, wherein an adhesion promoter is applied after the applicationof the polymeric preceramic precursor and before the said conversion ofthe polymeric preceramic precursor into the low-k sublayer.
 6. Themethod of claim 1, wherein anadhesion promoter is applied after the saidconversion of the polymeric preceramic precursor into the low-ksublayer.
 7. The method of claim 1, wherein a sacrificial moiety toproduce porosity is codissolved in a solution containing the polymericpreceramic precursor.
 8. The method of claim 1, wherein the applicationof the air barrier sublayer is by chemical vapor deposition processes,plasma enhanced chemical vapor deposition, or physical vapor deposition.9. The method of claim 1, wherein the air barrier sublayer is annealedby thermal curing, electron irradiation, ion irradiation, irradiationwith ultraviolet and/or visible light, or any combination thereof. 10.The method of claim 1, wherein an adhesion promoter is applied to theair barrier sublayer to enhance adhesion to other layers.
 11. The methodof claim 1, wherein the air barrier sublayer is exposed to a reactiveplasma to modify the surface of the air barrier sublayer in order toenhance adhesion to other layers.
 12. The method of claim 1, wherein thelow-k sublayer is exposed to a reactive plasma to modify the surface ofthe low-k sublayer in order to enhance adhesion to other layers.
 13. Acomposition for the generation of a multilayered dielectric diffusionbarrier layer comprising: a solvent for application of the low-ksublayer by a solvent based approach; a polymeric preceramic precursorthat is converted to a low-k sublayer; and an air barrier sublayer. 14.The composition of claim 13, wherein the polymeric preceramic precursorcomprises polysilazanes, polycarbosilanes, polysilasilazanes,polysilanes, polysilacarbosilanes, polysiloxazanes, polycarbosilazanes,polysilylcarbodiimides, polysilsesquiazanes or polysilacarbosilazanes.15. The composition of claim 13, wherein the polymeric preceramicprecursor includes pendant functional groups bonded to the chainbackbone, said pendent function groups are selected from the groupconsisting of amines, amides, imides, thioesters, thioethers, ureas,urethanes, nitriles, isocyanates, thiols, sulfones, phosphines,phosphine oxides, phosphonimides, benzotriazoles, pyridines, imidazoles,imides, oxazoles, benzoxazoles, thiazoles, pyrazoles, triazoles,thiophenes, oxadiazoles, thiazines, thiazoles, quionoxalines,benzimidazoles, oxindoles, indolines, hydride, vinyl, allyl, alkoxy,silyl and alkyl.
 16. The composition of claim 13, wherein the polymericpreceramic precursor has a composition of Si_(v)N_(w)C_(x)O_(y)H_(z)where 0.1≦v≦0.8, 0≦w≦0.8, 0.05≦x≦0.8, 0≦y<0.3, 0.05≦z≦0.8, andv+w+x+y+z=1.
 17. The composition of claim 13, wherein an antistriationagent is codissolved in the solution containing the polymeric preceramicprecursor to produce films of high uniformity.
 18. The composition ofclaim 13, wherein an adhesion promoter is codissolved in the solutioncontaining the polymeric preceramic precursor.
 19. The composition ofclaim 13, wherein a sacrificial moiety to produce porosity iscodissolved in the solution containing the polymeric preceramicprecursor.
 20. The composition of claim 13, wherein the low-k sublayerhas a composition of Si_(v)N_(w)C_(x)O_(y)H_(z) where 0.1≦v≦0.8,0≦w≦0.8, 0.05≦x≦0.8, 0≦y≦0.3, 0.05≦z≦0.8 for v+w+x+y+z=1.